The Plot: When the TARDIS materializes in a familiar junkyard in the 1960s, the Doctor and Steven are soon embroiled in a mystery in the City of London. Who are the mysterious bowler-hatted businessmen with their deadly umbrellas? And what secret is young Oliver Harper desperately trying to conceal?

Contracts have been signed. A deal is in place. And the Doctor discovers that perhaps not even he can stop a terrible business…

“Fungibility … you know, I love that word.”

This First Doctor story by very busy Big Finish contributor Simon Guerrier is narrated by Peter Purves as astronaut Stephen Taylor. This story is set immediately after the ghastly death of Sara Kingdom (whose first audio adventure, the truly classic Home Truths, also by Guerrier and featuring the same TARDIS team, I reviewed here), which has clearly traumatised both the Doctor and Stephen. Seemingly to help them overcome their grief and provide them with some sort of consolation (or so the Doctor thinks), the TARDIS takes them back to where it all began – the junkyard at Totter’s Lane in 1960s London. But before they two men can pay a visit to Ian and Barbara they come across an alien that looks a bit like a mushroom. Intrigued, they follow the creature to The City where they meet stockbroker Oliver Harper, a new regular character played by Tom Allen set to feature in a trilogy of Companion Chronicles.

Definition: Fungibility is the property of a good or a commodity whose individual units are capable of mutual substitution, such as crude oil, wheat, precious metals or currencies.

Oliver has just been alerted by a friend that the police are on to him – we are not sure quite what he has done, though we assume it must be some sort of insider trading, so he decides to make an exit. But while telling his boss that an emergency has come up at home, he discovers to his horror that the man appears to look a bit like a mushroom with red eyes. Despite his pressing need to escape the law, when he meets Steven and the Doctor he decides to investigate the alien presence and goes back to his firm. His boss, Mr Flowers, is just one of several members of an alien species, the Fulgurites, who are trading in one of the Earth’s main natural resources – its people! In the style of the original didactic remit of the show, this neat little story provides an imaginative look at the issue of slavery and its history as a legitimate practice of seafaring nations which traded in humans as they would any other commodity and then caps it with a moral lesson for its audience at its end.

Peter Purves and Tom Allen (Image: Big Finish)

This is a compact and highly amusing 60-minute play that has a lot going for it, not least Purves’ near-perfect rendition of William Hartnell. Also particularly good is the 60’s style musical score and a general Avengers atmosphere as bowler-hatted aliens chase our heroes wielding laser-firing umbrellas. Guerrier also contrives to provide the perfect ironic finale that serves to underline the main themes of the play. As its title suggests, this is a play that works on a couple of levels, the reference to financial tools (a perpetual bond is one that keeps paying dividends for an indeterminate period) but also referring to the friendship between the Doctor and his companions in the light of Sara’s shocking demise. The theme of slavery, cynically justified through ‘fungibility’ is also a smart little play on words as the Latin root (sic) of that fine if unusual word refers both to ‘performance’ but of course also to mushrooms. If this suggests a touch of levity, well, this is a fun little adventure that deals with heavy themes in a breezy and entertaining fashion and is all the better for it, though it doesn’t leave a lot of room for any deep emotions or soul-searching

On the downside it does feel like quite a modest offering, a little lacking in ambition and perhaps even a little constricted, limited as it is to one main setting, which may be typical of the TV series at the time but is obviously unnecessary on audio. But it tells its small story well, the acting is superb from both players and I greatly look forward to discovering just what Oliver’s secret is and seeing the dynamic between the three characters develop. The story continues in The Cold Equations.